428 MATER i A MEDIC A AND THERAPEUTICS. 



Diluted Mineral Acid, and constitute the first group of intes- 

 tinal astringents, called intestinal vascular astringents. 



c. Intestinal Constringents. The substances thus named 

 possess the property of coagulating or otherwise condensing 

 the gelatiniform and albuminous tissue supporting the small 

 vessels of themucosa, increasing its compactness, diminishing the 

 freedom of the circulation, and thus reducing the amount of 

 exudation through the vessel walls. Intestinal Constringents 

 are a very large group, including Persalts of Iron, Alum, 

 Sulphate of Copper, Oxide of Zinc, Tannin, and the numerous 

 vegetable products which yield it or some of its modifications, 

 such as Catechu, Kino, Krameria, and Cinnamon. 



3. Measures which influence Absorption and Excretion. a. 

 Saline Purgatives. Certain salts possess the property of greatly 

 disturbing the process of osmosis in the intestinal wall, such as 

 the Sulphates of Magnesia, Soda, and Potash; Phosphate of 

 Soda ; Tartrate, and Acid Tartrate of Potash ; and the Tartrate 

 of Soda and Potash. These produce two effects, namely, first, 

 increased flow of water from the intestinal vessels into 

 the cavity of the bowel, and consequently increased liquidity 

 of the stools: and secondly, a flow of the salts, with a 

 certain amount of water, from the cavity of the bowel into the 

 blood-vessels, whence it is partly carried away into the general 

 circulation, and partly again excreted into the bowel by the in- 

 testinal glands, once more to be absorbed. The result is an 

 abundant liquid stool ; in the case of Acid Tartrate of Potash, or 

 very large doses of the other salts, almost entirely watery. 

 The precise way in which these effects are produced by saline 

 substances is still obscure. They appear to be due in part to 

 the difference in specific gravity between the watery materials 

 in the bowel and the liquor sanguinis, in part to some specific 

 action of the salts upon the structures of the walls through 

 which they pass, depending on their chemical constitution and 

 affecting dialysis. According to some authorities, saline purga- 

 tives act in a measure by stimulating peristalsis. 



These salts furnish us with a ready means of increasing the 

 liquidity of the motions and the frequency of the stools, and 

 constitute the group called saline purgatives, the most powerful 

 of which are called hydragogue salines. 



Saline Astringents. A sufficient amount of salts, and (within 

 broad limits) a particular strength of solution, are required to 

 secure an abundant excretion ; otherwise their absorption in 

 watery solution is stimulated beyond their excretion, and 

 constipation instead of relaxation is the result. The same 

 effect is liable to be produced by their habitual employment. 

 We do not use this group of measures therapeutically. 



